x86/amd_node: Fix PCI device reference counting in amd_smn_init()grafted

The local "root" pointer is a temporary variable used during the device
search. Therefore, refcount related to the search iterators should be cleaned
up after the search is complete.

Use the __free() cleanup macro to ensure the refcount is decremented when the
temporary pointer goes out of scope.

Additionally, increment the refcount when caching a root pointer. This ensures
the in-use refcount is separate from the temporary search refcounting.

Finally, drop the redundant "root = NULL" before the second search loop. The
pci_get_class() iterator always decrements the refcount of its "from"
argument, so the first loop can only fall through with "root" already NULL.

Fixes: 0a4b61d9c2e4 ("x86/amd_node: Fix AMD root device caching")
Closes: https://sashiko.dev/#/patchset/20260806160159.230453-1-jason.andryuk%40amd.com
Reported-by: Sashiko <sashiko-bot@kernel.org>
Assisted-by: LLM
Signed-off-by: Yazen Ghannam <yazen.ghannam@amd.com>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Reviewed-by: Mario Limonciello (AMD) <superm1@kernel.org>
Cc: <stable@kernel.org>
Link: https://patch.msgid.link/20260903154325.74343-1-yazen.ghannam@amd.com

2 files changed, 73 insertions, 0 deletions

diff --git a/drivers/soc/gemini/Makefile b/drivers/soc/gemini/Makefile
new file mode 100644
index 000000000..8cbd1e45d
--- /dev/null
+++ b/drivers/soc/gemini/Makefile
@@ -0,0 +1,2 @@
+# SPDX-License-Identifier: GPL-2.0
+obj-y	+= soc-gemini.o
diff --git a/drivers/soc/gemini/soc-gemini.c b/drivers/soc/gemini/soc-gemini.c
new file mode 100644
index 000000000..642b96c91
--- /dev/null
+++ b/drivers/soc/gemini/soc-gemini.c
@@ -0,0 +1,71 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (C) 2017 Linaro Ltd.
+ *
+ * Author: Linus Walleij <linus.walleij@linaro.org>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2, as
+ * published by the Free Software Foundation.
+ *
+ */
+#include <linux/init.h>
+#include <linux/kernel.h>
+#include <linux/mfd/syscon.h>
+#include <linux/regmap.h>
+#include <linux/of.h>
+
+#define GLOBAL_WORD_ID				0x00
+#define GEMINI_GLOBAL_ARB1_CTRL			0x2c
+#define GEMINI_ARB1_BURST_MASK			GENMASK(21, 16)
+#define GEMINI_ARB1_BURST_SHIFT			16
+/* These all define the priority on the BUS2 backplane */
+#define GEMINI_ARB1_PRIO_MASK			GENMASK(9, 0)
+#define GEMINI_ARB1_DMAC_HIGH_PRIO		BIT(0)
+#define GEMINI_ARB1_IDE_HIGH_PRIO		BIT(1)
+#define GEMINI_ARB1_RAID_HIGH_PRIO		BIT(2)
+#define GEMINI_ARB1_SECURITY_HIGH_PRIO		BIT(3)
+#define GEMINI_ARB1_GMAC0_HIGH_PRIO		BIT(4)
+#define GEMINI_ARB1_GMAC1_HIGH_PRIO		BIT(5)
+#define GEMINI_ARB1_USB0_HIGH_PRIO		BIT(6)
+#define GEMINI_ARB1_USB1_HIGH_PRIO		BIT(7)
+#define GEMINI_ARB1_PCI_HIGH_PRIO		BIT(8)
+#define GEMINI_ARB1_TVE_HIGH_PRIO		BIT(9)
+
+#define GEMINI_DEFAULT_BURST_SIZE		0x20
+#define GEMINI_DEFAULT_PRIO			(GEMINI_ARB1_GMAC0_HIGH_PRIO | \
+						 GEMINI_ARB1_GMAC1_HIGH_PRIO)
+
+static int __init gemini_soc_init(void)
+{
+	struct regmap *map;
+	u32 rev;
+	u32 val;
+	int ret;
+
+	/* Multiplatform guard, only proceed on Gemini */
+	if (!of_machine_is_compatible("cortina,gemini"))
+		return 0;
+
+	map = syscon_regmap_lookup_by_compatible("cortina,gemini-syscon");
+	if (IS_ERR(map))
+		return PTR_ERR(map);
+	ret = regmap_read(map, GLOBAL_WORD_ID, &rev);
+	if (ret)
+		return ret;
+
+	val = (GEMINI_DEFAULT_BURST_SIZE << GEMINI_ARB1_BURST_SHIFT) |
+		GEMINI_DEFAULT_PRIO;
+
+	/* Set up system arbitration */
+	regmap_update_bits(map,
+			   GEMINI_GLOBAL_ARB1_CTRL,
+			   GEMINI_ARB1_BURST_MASK | GEMINI_ARB1_PRIO_MASK,
+			   val);
+
+	pr_info("Gemini SoC %04x revision %02x, set arbitration %08x\n",
+		rev >> 8, rev & 0xff, val);
+
+	return 0;
+}
+subsys_initcall(gemini_soc_init);